I really dig the photos that Silver Fox has in this post. I appears that her truck uses the same organizational system that mine do. That is, everything is spread out for maximum usage of available space and for easy finding.
Unfortunately, my coworkers were not terribly impressed by my truck organizational system. Something about "unprofessional" and "unsanitary".
But trucks and SUVs have all sorts of handy spaces to put the oddball things that you'd lose track of otherwise. Dashboard? Perfect for a laptop (as long as you're not leaving it alone). Drink holders? They work for water bottles, emergency whistle, migraine medication, the cell phone, a utility knife, and the spare pens that I always need. Back seat? That's for the extra sweaters, comfy non-steel toe shoes for driving, rain gear, and other "soft" stuff. Heavy stuff (hammers, toolkit, random metal bits) go on the floor. Everything else goes into the back. And yes, I do have a system for that.
It may look like a mess, but it keeps me from losing every little thing when I'm frazzled and don't have time to go searching for it.